The cable goes into the top of the carb and attaches to the slide. It requires either one of Lancer's cables for the VM kit or modifying the stock cable to work with the PWK.

The second gotcha with the PWK is that the hose from the airbox to the carburetor is too short, and it needs to be turned backward with the big end going to the PWK. Cut a short piece of PVC pipe to go from the airbox to the small end of that hose and you are set. DragBikeMike's testing showed that you will need the cylindrical air filter with it for best results because the stock filter is too restrictive for the increased flow. That can be fitted within the airbox, see his evolution of a hotrod thread for the details on that.

Like this.

But you have to hook the cable when the little contraption is installed in the slide, and then drop the sleeve and spring down over the cable and contraption.  It's a juggling act to say the least.  It's kinda tight down there between the contraption and the slide.

You need a 6mm socket to remove the contraption.  You have to take the contraption out in order to adjust the slide needle clip.

Dan, it all depends on your skill level.  If you have limited experience and skill, then the Mikuni VM that Lancer sells is your best choice.  The kit he puts together has everything you need to install the carburetor, and there are lots of forum members running the VM, so help and advice will be plentiful.

The Keihin PWK works great but you have to gather up the parts piecemeal.  It's a lot cheaper but you have to do the extra work gathering parts.  The throttle cable is also is a bit more difficult to set up.

Both of the carbs work extremely well.  The Keihin flows a bit more air so you get just a bit more power.  The Mikuni is a bit more versatile in the tuning department because it has a removable needle jet and main air bleed.  However both carbs are very easy to dial in.

I have run the VM38, PWK38 and PWK36 all with excellent results.  

This post will give you some insight on how the VM & PWK compare to each other.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1585461605

And this post will provide a little more detail on installing a PWK38 on a stock engine.  It will also give you a good baseline for jets and an idea of what to expect in terms of performance.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1625732492

No matter what you choose, stock, VM or PWK, I'm sure the folks on this forum stand ready to help you get it up & runnin.

Good luck, Mike

Mine is supposed to arrive today as well!

Mine didn't come with any stamp indicating size.  You are right, there seems to be a lot of variation when buying these.